It is well known to construct energy-efficient windows using insulating glazing devices in order to reduce the flow of heat through the windows. Insulating glazing devices typically comprise two or more parallel glass sheets (also called “panes” or “lights”) separated by a narrow gap (i.e., space) and sealed around their periphery. When the inter-pane space is filled with air or another gas at near-atmospheric pressure, the device is commonly called an insulating glazing unit, insulated glass unit or IGU. When the inter-pane space is evacuated (or partly evacuated), the device is commonly called a vacuum insulating glazing unit, vacuum insulated glass unit or VIGU.
Examples of insulated glazing devices are disclosed in U.S. Patent Application Publication No. 2006/0187608 A1, titled Insulated Glazing Units, published Aug. 24, 2006, and U.S. Patent Application Publication No. 2006/0191215, titled Insulated Glazing Units and Methods, published Aug. 31, 2006, by inventor David H. Stark, both applications being hereby incorporated herein by reference. These applications describe the need for VIGUs to have an arrangement at the edges of the glass to form a seal between the two panes of glass, and disclose various embodiments to address this need.
It is generally understood by those who are skilled in the art, that an in-situ VIGU will be subjected to a variety of mechanical, thermal and chemical stresses, all acting simultaneously with varying levels of intensity, throughout the operating lifetime of the VIGU. The nature and magnitude of these stresses are also understood.
It is also generally understood by those skilled in the art that since the VIGU assembly incorporates several discrete elements, which each embody characteristic geometry and thermal expansion properties, and all of these elements are subsequently joined together by some means, the resulting mechanical system will react to stresses in a complex manner. For instance, a single pane of glass subjected to cold exterior and warm interior temperatures would be expected to exhibit a fairly simple pattern of internal stresses as a result of this condition. However, a VIGU, subjected to the same cold and warm temperature conditions would exhibit a much more complex stress pattern, especially at the edges where the inner and outer panes are joined together by some means.
It can readily be observed that insulating glass units (IGU) all embody a flexible sealant at the outer edge of the glass, which readily deflects slightly to relieve the stresses that occur during exposure to the aforementioned stresses. IGUs are generally described as inner and outer glass pane assemblies with gas in the gap between the panes and are in common use in the marketplace.
It can also be readily observed that VIGUs with edge seals formed by rigid materials exhibit significant deflections when subjected to cold external and warm internal temperature conditions. The observed deflections are caused by transient stresses, which are locked in place by the rigid edge seals. Further observations can be made that these deflections in some cases, cause the window assembly to deflect, bind up and become non-functional—a serious issue in the case of situations requiring egress through the window. Long term issues involving edge seal failures due to the high stresses are anticipated, but are not characterized at the present time.
A need therefore exists, for a flexible edge seal (FES) element that seals the space between the glass sheets of an IGU or VIGU while accommodating the transient stresses and mitigating the effects of temperature differentials between cold and warm environments.